Apparatus for the control of highway crossing signals



P. P. STOKER Sept. 6, 1938.

APPARATUS FOR THE CONTROL OF HIGHWAY CROSSING SIGNALS Filed Sept. 14, 1935 INVENTOR Paul R Stoker. fi/RW m5 ATTORNEY Patented Sept. 6, 1938 UNITED STATES APPARATUS FOR THE CONTROL OF HIGH- WAY CROSSING SIGNALS Paul P. Stoker, Wilkinsburg, Pa., assignor to The Union Switch & Signal Company, Swissvale, Pa., a corporation of Pennsylvania Application September 14, 1935, Serial No. 40,596

Claims.

My invention relates to apparatus for the control of highway crossing signals, and has for an,

object the provision of novel and improved apparatus for governing the operation of a highway crossing signal which is capable of displaying three separate and distinctive indications.

I will describe one form of apparatus embodying my invention, and will then point out the novel features thereof in claims.

For a better understanding of my invention, reference may be had to the accompanying drawing which is a preferred form of circuits and apparatus embodying my invention.

Referring to the drawing, the reference characters I and I designate the traffic rails of a stretch of railway over which traffic moves in either direction and which is intersected by a highway H. The trafiic rails I and I are divided by the usual insulated rail joints to form two track sections IT and 2T, the arrangement being such that thejunction of these two track sections is adjacent the highway. The maximum allowable speed over this stretch of railway and the warning period desired prior to the arrival of a train at the intersection determine the length of the track sections IT and 2T, since, as will appear later, a warning to highway users is initiated upon entrance of a train into a track section at the end of the section remote from the highway. The two track sections IT and 2T are each provided with a track circuit. As here shown, the track circuit for section IT includes a battery 2 connected across the rails at the left-hand end of the section and the winding 3 of an interlocking relay IR to be referred to later connected across the rails at the right-hand end of the section. The circuit for section 2T includes a battery 4 connected across the rails at the right-hand end of the section and the winding 5 of relay IR connected across the rails at the left-hand end of the section. i i

The specific form of interlocking relay is immaterial, and it may be assumed to be of the type described in United States Letters Patent No. 799,452, granted September 12, 1905, to W. W. Coleman, for a Relay. It is deemed sufficient for the present description to point out that the circuit controlling armatures 6 and I of relay IR are controlled by the windings. 3 and 5, respectively, and are provided with an interlocking mechanism not shown whereby the movement of one armature may govern the movement of the other armature. The armatures 6 and I are normally held in engagement with front contacts 8 and 9, respectively, by virtue of energization of the respective windings 3 and 5. The deenergizaticn of winding 3 while winding 5 remains energized releases armature 6 and that armature drops to break engagement with contact 8 and to operate the interlocking mechanism. With arma ture 5 in its full down position and the interlocking mechanism operatedand the winding 5 is deenergized to release armature I, the armature is prevented from breaking engagement with contact 9 by the interlocking mechanism, the interlocking mechanism being effective to retain armature I in engagement with contact 9 notwithstanding the fact that winding 3 may be subsequently reenergized and its armature 6 picked up while the winding 5 still remains deenergized.

Reenergizing winding 5 is effective, however, to

restore the interlocking mechanism to its normal position the same as explained in connection with winding 5.

. A highway signal Sis located adjacent the intersection. As here shown, this signal S consists of a. green lamp G, a. yellow lamp Y and a red lamp R. The green lamp G is illuminated when no train is approaching the intersection within the limits of the stretch of railway under consideration to display a clear traffic signal to highway users about to pass over the crossing. The yellowlamp Y is illuminated when a train approaching the intersection enters the track section on. the side of the highway approached, and this lamp is displayed for a predetermined time interval to warn highway users a train is approaching tions of signal S correspond to the customary green, yellow and red trafiic light signals encountered along a highway. In practicing my invention, the signal S will be set to be plainly exhibited in both directions, or two such signals may be provided and set facing in opposite directions. The lamps of such second signal would be arranged in multiple with the respective lamps. of signal S. It will be understood, of course, that my invention is not limited to this one form of highway trafiic signal and other types of traffic signals which are capable of displaying the three indications, clear, warning, and stop, may be used ii desired.

- tery terminal.

In addition to the track circuits described hereinbefore, the signal control apparatus consists of relays A and D and a time measuring device TH.

The relays A and D are preferably of the direct current neutral type, the relay D being slightly slow'releasing in character.

The time measuring device may take different forms several of which are well known to the art, among them being a thermal relay. As here shown, the time measuring device TH is a thermal relay provided with a normally closed contact which is adapted to be operated to an open position in a predetermined time interval when the heater element of the relay is supplied with current. I shall assume the relay TH is so proportioned and adjusted that when the heater element II) has been supplied with current for a period of 10 seconds, the contact member II is drawn to the left, as viewed in the drawing, out of engagement with a stationary contact I2 to open the circuit connection therethrough. It will be understood, of course, other periods of operation of the time measuring device may be selected if desired.

In describing the operation of the apparatus, I shall first assume no train is approaching the highway H, that is, the track sections IT and ET are both unoccupied, and the apparatus is in the' position illustrated. Under these circumstances, the G lamp of signal S is illuminated by virtue of a circuit extending from the 3 terminal of any convenient source of current such as a battery not shown over front contact I3 of relay A, wire I4, lamp G, and to the C terminal of the same source of current. Hence, the green lamp G is continuously displayed by signal S when no train is approaching the intersection within the limits of the stretch of railway under consideration to indicate a clear traffic condition for the highway.

I will next describe the operation which takes place when a train approaches the highway from the left-hand side as viewed in the drawing. When the train enters the section IT and shunts the winding 3 of relay IR, the armature 6 is released and falls out of engagement with front contact 8 and operates the interlocking mechanism of the relay as explained hereinbefore. The repeater relay A, which is normally energized over a circuit traced from the B battery terminal, contact I5 to be referred to later, wire I6, contacts 68 and '|9 of relay IR, winding of relay A and to the C battery terminal, is released since its circuit is now open at the contact 68. The relay A upon being released opens the circuit to lamp G at the front contact I3 and the clear trafiic signal for the highway is extinguished. The release of relay A completes two circuits one of which is effective to supply current to the Y lamp of signal S and the other of which is effective to supply current to the heater element III of thermal relay TH. The circuit for 'the heater element II! includes battery terminal B, back contact 23 of relay A, front contact 24 of relay D, heater element It and to the C bat- The circuit for the Y lamp includes battery terminal B, back contact I! of relay A, front contact I8 of relay D, wire I9, Y lamp of signal S and to the C battery terminal. The relay D which is normally energized over a simple circuit including front contact 2E! of relay A is, upon release of relay A, retained energized by virtue of a stick circuit which includes the B battery terminal, back contact 2! of relay A, contact II-IZ of thermal relay TH, front contact 22 of relay D, winding of that relay and to the C battery terminal. As set forth hereinbefore, the thermal relay TH is so proportioned and adjusted that the contact III2 is operated substantially 10 seconds following the supply of current to the heater element II], it being understood, of course, that the current source is of proper voltage and capacity to deliver the desired current flow. When the relay TH is operated and its contact III2 is opened, the stick relay D is without current and releases at the end of its slow release period since both its stick circuit and its pickup circuit are now open. Relay D upon releasing opens the circuit to the heater element In at the front contact 24 and the relay TH quickly cools and its contact III2 is restored to its normal closed position. The

. release of stick relay D is also eifective to extinguish the Y lamp and to illuminate the stop lamp R. With relay D down, the R lamp is supplied with current over a circuit extending from the B battery terminal, back contact I! of relay A, back contact 25 of relay D, wire 26, lamp R and to the C battery terminal. Consequently, the Y lamp of signal S is illuminated for 10 secends-subsequent to the train entering the section IT to display a warning signal, and at the end of this 10 second period the Y lamp is extinguished and the stop lamp R is illuminated to indicate stop for traffic on the highway.

When the head end of the train proceeds over the highway and enters the track section 2T and shunts the winding 5 of relay R, the contact 'I--9 of relay IR is held closed by the interlocking mechanism of the relay as explained hereinbefore. Consequently, as soon as the rear of the train passes to the right of the highway and vacates the traction section IT and the winding 3 is reenergized and its contact 68 is closed, the repeater relay A is picked up and its front contact I3 is closed. Thus, the stop lamp R is extinguished and the green lamp G is again illuminated immediately following the passing of the therefore, that a clear traffic signal for the highway is normally displayed by signal S, a warning or prepare to stop indication is displayed for a predetermined period when a train approaching the highway H enters the section IT and a stop indication is displayed subsequent to the expiration of such period until the train has passed beyond the intersection. Furthermore, the warning or prepare to stop signal is not displayed when the indication is being changed from stop back to clear.

It is apparent that the signal S is governed in a similar manner in response to a train advancing through the stretch of railway from the right to the left, except for the fact that the contact 'I9 of relay IR is opened when the train enters the section ET and the contact 68 is held closed by the interlocking meechanism of. the relay as the train recedes from the intersection.

The contact I5 may be a manually operated circuit controller located in any nearby signal tower and by means of which operation of the signal S may be governed since contact I 5 is interposed in the energizing circuit for the repeater relay A. It is clear that operation of the contact I5 is effective to operate relay A and set in operation thermal relay TH to govern the stick relay D and the signal S the same as explained in connection with a train approaching the highway.

Although I have herein shown and described only one form of apparatus embodying my invention, it is understood that various changes and modifications may be made therein within the scope of the appended claims without departing from the spirit and scope of my invention.

Having thus described my invention, what I claim is:

1. In combination, a stretch of railway track intersected by a highway, a highway signal consisting of a green lamp and a yellow lamp as well as a red lamp located adjacent the intersection, a track section on at least one side of the highway, a'track circuit including a track relay for the section, a normally inactive time measuring device including a normally closed contact adapted to be opened a predetermined time interval subsequent to the device set into operation, a stick relay provided with a pickup circuit including a contact closed when the track relay is energized and a stick circuit including the contact of said timing device, means including a front contact of the track relay and the green lamp to display a clear indication for the highway, means controlled by the track relay when deenergized to set the timing device into operation, means including a front contact of the stick relay and said yellow lamp as well as a contact closed when the track relay is deenergized to display a warning indication for the highway, and means including a back contact of said stick relay and the red lamp to display a stop indication for the highway.

2. In combination, a stretch of railway track intersected by a highway, a highway signal consisting of a green lamp and a yellow lamp as well as a red lamp located adjacent the intersection, a

track section on at least one side of the highway, a i trackcircuit including a track relay for the section, a thermal relay including a normally closed contact adapted to be operated a predetermined time interval subsequent to current supplied to the relay, a stick relay provided with a pickup circuit including a contact closed when the track relay is energized and a stick circuit including the contact of said thermal relay, means including a front contact of the track relay and the green lamp to display a clear indication for the highway, means controlled by the track relay effective when the track relay is deenergized to supply current to the thermal relay, means including a front contact of the stick relay and the yellow lamp as well as a contact closed when the track relay is deenergized to display a warning indication for the highway, and means including a back contact of the stick relay and the red lamp to display a stop indication for the highway.

3. In combination, a stretch of railway track formed into two track sections and intersected by a highway at the junction of the sections, a highway signal consisting of a green lamp and a yellow lamp as well as a red lamp located at the intersection, a track circuit for each section, each circuit including a winding of an interlocking relay, a repeater relay, a circuit for energizing said repeater relay including a front contact of each of the two windings of the interlocking relay, a thermal relay including a normally closed contact adapted to be operated a predetermined time interval subsequent to current supplied to the relay, a stick relay having a pickup circuit including a front contact of the repeater relay and a stick circuit including the contact of said thermal relay, a first circuit including the green lamp and a front contact of the repeater relay for causing said signal to display a clear indication, means including a back contact of the repeater relay for supplying current to the thermal relay only when a train enters a section in approaching the highway, a second circuit including a front contact of the stick relay and the yellow lamp as well as a back contact of the repeater relay for causing the signal to display a warning indication, and a third circuit including a back contact of the stick relay and the red lamp for causing the signal to display a stop indication.

4. In combination, a stretch of railway track formed into two track sections and intersected by a highway at the junction of the sections, a highway signal consisting of a green lamp and a yellow lamp as well as a red lamp located at the intersection, a track circuit for each section, each circuit including a winding of an interlocking relay, a repeater relay, a circuit including a front contact of each of the two windings of the interlocking relay and a winding of the repeater relay for energizing the repeater relay whereby said repeater relay is deenergized only when a train enters a section in approaching the highway, a thermal relay including a normally closed contact adapted to be operated a predetermined time interval subsequent to current supplied to the relay, a stick relay, a pickup circuit for the stick relay including a front contact of the repeater relay, a stick circuit for said stick relay including the contact of said thermal relay, a first circuit including the green lamp and a front contact of the repeater relay for causing said signal to display a clear indication, means including a back contact of the repeater relay for supplying current to the thermal relay, a second circuit including a front contact of the stick relay and the yellow lamp as well as a back contact of the repeater relay for causing said signal to display a warning indication, and a third circuit including a back contact of the stick relay and the red lamp for causing said signal to display a stop indication.

5. In combination, a stretch of railway track formed into two insulated track sections which are intersected by a highway adjacent their junction, highway crossing signaling means adaptable of displaying a clear and a warning as well as a stop indication, an interlocking relay, a track circuit for each section including a particular magnet winding of the relay, a time measuring device provided with a normally closed contact which is opened a predetermined time interval subsequent to the device set into operation, a stick relay, pickup circuit means for said stick relay including a front contact of each magnet of the interlocking relay, a stick circuit for said stick relay including said contact of the time measuring device, means controlled by the interlocking relay to set said device into operation when a train approaching the intersection enters the section on the side approached, other means controlled by the interlocking relay to cause the signaling means to display the clear indication only when both of said magnets are energized, means controlled by the interlocking relay and the stick relay to cause the signaling means to display the warning indication when either one of said magnets is deenergized in response to a train approaching the intersection and the stick relay is energized, and means controlled by the stick relay when deenergized to cause the signaling means to display the stop indication.

PAUL P. STOKER. 

